The present disclosure relates generally to wellsite operations. In particular, the present disclosure relates to formation evaluation, such as sensing downhole properties.
Wellbores are drilled to locate and produce hydrocarbons. A downhole drilling tool with a bit at an end thereof is advanced into the ground to form a wellbore. As the drilling tool is advanced, drilling mud is pumped through the drilling tool and out the drill bit to cool the drilling tool and carry away cuttings. The fluid exits the drill bit and flows back up to the surface for recirculation through the drilling tool. The drilling mud is also used to form a mudcake to line the wellbore.
During or after a drilling operation, various downhole evaluations may be performed to determine characteristics of the wellbore and surrounding formation. In some cases, the drilling tool may be provided with devices to test the surrounding formation. In some cases, the drilling tool may be removed and a downhole wireline tool may be deployed into the wellbore to test the formation. These tests may be used, for example, to determine whether valuable hydrocarbons are present. Production equipment may be positioned in the wellbore to draw located hydrocarbons to the surface.
Formation evaluation may involve positioning sensors in the wellbore to take downhole measurements for the formation. Downhole tools may be provided with sensors for measuring downhole parameters. Examples of sensors are provided in U.S. Pat. No. 6,170,601 and U.S. Pat. No. 6,997,258.